CTV/National Angus Reid Poll - Infidelity:
http://www.angusreid.com/media/content/displaypr.cfm
?id_to_view=896
and
http://www.angusreid.com/media/content/displaypr.cfm
?id_to_view=895

Also see:
Marital Infidelity
http://www.angusreid.com/media/content/displaypr.cfm
?id_to_view=1186